Soybean Looper

John Van Duyn, North Carolina State University, Entomology Extension Specialist

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Soybean looper larva (Clemson)
Black legged soybean looper larva

Soybean looper:This defoliating caterpillar pest is a year- around resident of more southern areas, but it migrates into NC each year. The immigration pattern is typically along the coast from south to north and spreading inland. Coastal counties south of Cape Lookout have the highest likelihood of economic infestation, although in some years infestations may spread above the Albemarle Sound and inland to I-95. The moth is a dark brown robust moth with a small silver-white figure eight spot on each forewing. Larvae are green with whitish lines along the length of the body and three pair of fleshy prolegs. The body of the larvae is tapered from the rear (largest) forward to the head. Often the true legs and head are black. Larvae crawl with a distinct looping motion and may rest in this pose. The sluggish caterpillar favors the lower plant canopy and leaf underside, but will feed over the entire plant as defoliation progresses.

Soybean looper moth populations peak in late August. Moths colonize soybean and cotton fields. High infestation is often associated with the removal of predators and parasites by insecticide use for corn earworm (bollworm) control. Also, research has shown that moths feeding on cotton nectaries develop and lay many more eggs, resulting in higher populations in the vicinity of cotton fields. Peak larval populations occur in September, mostly on later planted soybeans. This caterpillar is a voracious feeder and high populations can completely strip the foliage from fields; they do not feed on pods. Late planted, double crop soybeans are the most susceptible.

Frequently, soybean looper is difficult to kill since most populations are resistant to most soybean insecticides. Also, due to their habit of staying low in the canopy, on the leaf underside, insecticide performance is often negatively affected by poor coverage.

Soybean Page


Other Resources

  1. North Carolina Agricultural Chemicals Manual
  2. North Carolina Cooperative Extension Service

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This page (http://www.ces.ncsu.edu/plymouth/pubs/looper.html) was created by John W. Van Duyn Ph D. Extension Entomologist, Wayne Modlin, Res. Tech. III.

Date Created 2/22/00.
Last revised on 2/04/04.

Published by North Carolina Cooperative Extension Service

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

CAUTION: The information and recommendations in these Notes were developed for North Carolina conditions and may not apply elsewhere.